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Li M, Liu M, Qi F, Lin FR, Jen AKY. Self-Assembled Monolayers for Interfacial Engineering in Solution-Processed Thin-Film Electronic Devices: Design, Fabrication, and Applications. Chem Rev 2024; 124:2138-2204. [PMID: 38421811 DOI: 10.1021/acs.chemrev.3c00396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/02/2024]
Abstract
Interfacial engineering has long been a vital means of improving thin-film device performance, especially for organic electronics, perovskites, and hybrid devices. It greatly facilitates the fabrication and performance of solution-processed thin-film devices, including organic field effect transistors (OFETs), organic solar cells (OSCs), perovskite solar cells (PVSCs), and organic light-emitting diodes (OLEDs). However, due to the limitation of traditional interfacial materials, further progress of these thin-film devices is hampered particularly in terms of stability, flexibility, and sensitivity. The deadlock has gradually been broken through the development of self-assembled monolayers (SAMs), which possess distinct benefits in transparency, diversity, stability, sensitivity, selectivity, and surface passivation ability. In this review, we first showed the evolution of SAMs, elucidating their working mechanisms and structure-property relationships by assessing a wide range of SAM materials reported to date. A comprehensive comparison of various SAM growth, fabrication, and characterization methods was presented to help readers interested in applying SAM to their works. Moreover, the recent progress of the SAM design and applications in mainstream thin-film electronic devices, including OFETs, OSCs, PVSCs and OLEDs, was summarized. Finally, an outlook and prospects section summarizes the major challenges for the further development of SAMs used in thin-film devices.
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Affiliation(s)
- Mingliang Li
- Department of Materials Science and Engineering, City University of Hong Kong, Kowloon, Hong Kong 999077, China
- Hong Kong Institute for Clean Energy, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Ming Liu
- Department of Materials Science and Engineering, City University of Hong Kong, Kowloon, Hong Kong 999077, China
- Hong Kong Institute for Clean Energy, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Feng Qi
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
- Hong Kong Institute for Clean Energy, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Francis R Lin
- Department of Materials Science and Engineering, City University of Hong Kong, Kowloon, Hong Kong 999077, China
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
- Hong Kong Institute for Clean Energy, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Alex K-Y Jen
- Department of Materials Science and Engineering, City University of Hong Kong, Kowloon, Hong Kong 999077, China
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
- Hong Kong Institute for Clean Energy, City University of Hong Kong, Kowloon, Hong Kong 999077, China
- Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98195, United States
- State Key Laboratory of Marine Pollution, City University of Hong Kong, Kowloon, Hong Kong 999077, China
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Ikeda T, Tahara K, Kadoya T, Tajima H, Toyoda N, Yasuno S, Ozawa Y, Abe M. Ferrocene on Insulator: Silane Coupling to a SiO 2 Surface and Influence on Electrical Transport at a Buried Interface with an Organic Semiconductor Layer. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:5809-5819. [PMID: 32407106 DOI: 10.1021/acs.langmuir.0c00515] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
A silane coupling-based procedure for decoration of an insulator surface containing abundant hydroxy groups by constructing redox-active self-assembled monolayers (SAMs) is described. A newly synthesized ferrocene (Fc) derivative containing a triethoxysilyl group designated FcSi was immobilized on SiO2/Si by a simple operation that involved immersing the substrate in a toluene solution of the Fc silane coupling reagent and then rinsing the resulting substrate. X-ray photoelectron spectroscopy (XPS) measurements confirmed that the Fc group was immobilized on SiO2/Si in the Fe(II) state. Cyclic voltammetry measurements showed that the Fc groups were electrically insulated from the Si electrode by the SiO2 layer. The FcSi on SiO2/Si structures were found to serve as a good scaffold for formation of organic semiconductor thin films by vacuum thermal evaporation of C8-BTBT (2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene), which is well-known as an organic field-effect transistor (OFET) material. The X-ray diffraction profile indicated that the conventional standing-up conformation of the C8-BTBT molecules perpendicular to the substrates was maintained in the thin films formed on FcSi@SiO2/Si. Further vacuum thermal evaporation of Au provided an FcSi-based OFET structure with good transfer characteristics. The FcSi-based OFET showed pronounced source-drain current hysteresis between the forward and backward scans. The degree of this hysteresis was varied reversibly via gate bias manipulation, which was presumably accompanied by trapping and detrapping of hole carriers at the Fc-decorated SiO2 surface. These findings provide new insights into application of redox-active SAMs to nonvolatile OFET memories while also creating new interfaces through junctions with functional thin films, in which the underlying redox-active SAMs play supporting roles.
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Affiliation(s)
- Takashi Ikeda
- Graduate School of Material Science, University of Hyogo, 3-2-1, Kouto, Kamigori, Ako, Hyogo 678-1297, Japan
| | - Keishiro Tahara
- Graduate School of Material Science, University of Hyogo, 3-2-1, Kouto, Kamigori, Ako, Hyogo 678-1297, Japan
| | - Tomofumi Kadoya
- Graduate School of Material Science, University of Hyogo, 3-2-1, Kouto, Kamigori, Ako, Hyogo 678-1297, Japan
| | - Hiroyuki Tajima
- Graduate School of Material Science, University of Hyogo, 3-2-1, Kouto, Kamigori, Ako, Hyogo 678-1297, Japan
| | - Noriaki Toyoda
- Graduate School of Engineering, University of Hyogo, 2167, Shosha, Himeji, Hyogo 671-2280, Japan
| | - Satoshi Yasuno
- Japan Synchrotron Radiation Research Institute, 1-1-1, Kouto, Sayo, Hyogo 679-5198, Japan
| | - Yoshiki Ozawa
- Graduate School of Material Science, University of Hyogo, 3-2-1, Kouto, Kamigori, Ako, Hyogo 678-1297, Japan
| | - Masaaki Abe
- Graduate School of Material Science, University of Hyogo, 3-2-1, Kouto, Kamigori, Ako, Hyogo 678-1297, Japan
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Igari T, Imamura K, Yasumura K, Iwasa T, Sakakibara K, Yamaguchi K. Synthesis of Photodegradable Surface Modifiers Based on Phosphonic Acid for Introducing Functional Groups onto a Substrate and Application for Patterned Deposition of Gold Nano-Particulate Ink. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2019. [DOI: 10.1246/bcsj.20180391] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Takuma Igari
- Department of Chemistry, Kanagawa University, Tsuchiya, Hiratsuka, Kanagawa 259-1293, Japan
| | - Kana Imamura
- Department of Chemistry, Kanagawa University, Tsuchiya, Hiratsuka, Kanagawa 259-1293, Japan
| | - Kenta Yasumura
- Department of Chemistry, Kanagawa University, Tsuchiya, Hiratsuka, Kanagawa 259-1293, Japan
| | - Tomoki Iwasa
- Department of Chemistry, Kanagawa University, Tsuchiya, Hiratsuka, Kanagawa 259-1293, Japan
| | - Kazuki Sakakibara
- Department of Chemistry, Kanagawa University, Tsuchiya, Hiratsuka, Kanagawa 259-1293, Japan
| | - Kazuo Yamaguchi
- Department of Chemistry, Kanagawa University, Tsuchiya, Hiratsuka, Kanagawa 259-1293, Japan
- Research Institute for Photofunctionalized Materials, Kanagawa University, Tsuchiya, Hiratsuka, Kanagawa 259-1293, Japan
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Hou X, Cheng X, Zhou J, He J, Xu Q, Li H, Li N, Chen D, Lu J. Better Organic Ternary Memory Performance through Self‐Assembled Alkyltrichlorosilane Monolayers on Indium Tin Oxide (ITO) Surfaces. Chemistry 2017; 23:16393-16400. [DOI: 10.1002/chem.201704059] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Indexed: 11/05/2022]
Affiliation(s)
- Xiang Hou
- College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Suzhou Nano Science and Technology Institution Soochow University Suzhou 215123 P. R. China
| | - Xue‐Feng Cheng
- College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Suzhou Nano Science and Technology Institution Soochow University Suzhou 215123 P. R. China
| | - Jin Zhou
- College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Suzhou Nano Science and Technology Institution Soochow University Suzhou 215123 P. R. China
| | - Jing‐Hui He
- College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Suzhou Nano Science and Technology Institution Soochow University Suzhou 215123 P. R. China
| | - Qing‐Feng Xu
- College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Suzhou Nano Science and Technology Institution Soochow University Suzhou 215123 P. R. China
| | - Hua Li
- College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Suzhou Nano Science and Technology Institution Soochow University Suzhou 215123 P. R. China
| | - Na‐Jun Li
- College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Suzhou Nano Science and Technology Institution Soochow University Suzhou 215123 P. R. China
| | - Dong‐Yun Chen
- College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Suzhou Nano Science and Technology Institution Soochow University Suzhou 215123 P. R. China
| | - Jian‐Mei Lu
- College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Suzhou Nano Science and Technology Institution Soochow University Suzhou 215123 P. R. China
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Paniagua SA, Giordano AJ, Smith OL, Barlow S, Li H, Armstrong NR, Pemberton JE, Brédas JL, Ginger D, Marder SR. Phosphonic Acids for Interfacial Engineering of Transparent Conductive Oxides. Chem Rev 2016; 116:7117-58. [DOI: 10.1021/acs.chemrev.6b00061] [Citation(s) in RCA: 142] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Sergio A. Paniagua
- School
of Chemistry and Biochemistry and Center for Organic Photonics and
Electronics, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States
| | - Anthony J. Giordano
- School
of Chemistry and Biochemistry and Center for Organic Photonics and
Electronics, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States
| | - O’Neil L. Smith
- School
of Chemistry and Biochemistry and Center for Organic Photonics and
Electronics, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States
| | - Stephen Barlow
- School
of Chemistry and Biochemistry and Center for Organic Photonics and
Electronics, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States
| | - Hong Li
- School
of Chemistry and Biochemistry and Center for Organic Photonics and
Electronics, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States
- Division
of Physical Sciences and Engineering, King Abdullah University of Science and Technology, KAUST, Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Neal R. Armstrong
- Department
of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
| | - Jeanne E. Pemberton
- Department
of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
| | - Jean-Luc Brédas
- School
of Chemistry and Biochemistry and Center for Organic Photonics and
Electronics, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States
- Division
of Physical Sciences and Engineering, King Abdullah University of Science and Technology, KAUST, Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - David Ginger
- Department
of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Seth R. Marder
- School
of Chemistry and Biochemistry and Center for Organic Photonics and
Electronics, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States
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6
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Forget A, Limoges B, Balland V. Efficient chemisorption of organophosphorous redox probes on indium tin oxide surfaces under mild conditions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:1931-1940. [PMID: 25611977 DOI: 10.1021/la503760x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We report a mild and straightforward one-step chemical surface functionalization of indium tin oxide (ITO) electrodes by redox-active molecules bearing an organophosphoryl anchoring group (i.e., alkyl phosphate or alkyl phosphonate group). The method takes advantage of simple passive adsorption in an aqueous solution at room temperature. We show that organophosphorus compounds can adsorb much more strongly and stably on an ITO surface than analogous redox-active molecules bearing a carboxylate or a boronate moiety. We provide evidence, through quantitative electrochemical characterization (i.e., by cyclic voltammetry) of the adsorbed organophosphoryl redox-active molecules, of the occurrence of three different adsorbate fractions on ITO, exhibiting different stabilities on the surface. Among these three fractions, one is observed to be strongly chemisorbed, exhibiting high stability and resistance to desorption/hydrolysis in a free-redox probe aqueous buffer. We attribute this remarkable stability to the formation of chemical bonds between the organophosphorus anchoring group and the metal oxide surface, likely occurring through a heterocondensation reaction in water. From XPS analysis, we also demonstrate that the surface coverage of the chemisorbed molecules is highly affected by the degree of surface hydroxylation, a parameter that can be tuned by simply preconditioning the freshly cleaned ITO surfaces in water. The lower the relative surface hydroxide density on ITO, the higher was the surface coverage of the chemisorbed species. This behavior is in line with a chemisorption mechanism involving coordination of a deprotonated phosphoryl oxygen atom to the non-hydroxylated acidic metal sites of ITO.
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Affiliation(s)
- Amélie Forget
- Laboratoire d'Electrochimie Moléculaire, UMR CNRS 7591, Université Paris Diderot , Sorbonne Paris Cité, 15 rue Jean-Antoine de Baïf, F-75205 Paris, Cedex 13, France
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Lamberti F, Agnoli S, Brigo L, Granozzi G, Giomo M, Elvassore N. Surface functionalization of fluorine-doped tin oxide samples through electrochemical grafting. ACS APPLIED MATERIALS & INTERFACES 2013; 5:12887-12894. [PMID: 24171474 DOI: 10.1021/am403292x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Transparent conductive oxides are emerging materials in several fields, such as photovoltaics, photoelectrochemistry, and optical biosensing. Their high chemical inertia, which ensured long-term stability on one side, makes challenging the surface modification of transparent conductive oxides; long-term robust modification, high yields, and selective surface modifications are essential prerequisite for any further developments. In this work, we aim at inducing chemical functionality on fluorine-doped tin oxide surfaces (one of the most inexpensive transparent conductive oxide) by means of electrochemical grafting of aryl diazonium cations. The grafted layers are fully characterized by photoemission spectroscopy, cyclic voltammetry, and atomic force microscopy showing linear correlation between surface coverage and degree of modification. The electrochemical barrier effect of modified surfaces was studied at different pH to characterize the chemical nature of the coating. We showed immuno recognition of biotin complex built onto grafted fluorine-doped tin oxides, which opens the perspective of integrating FTO samples with biological-based devices.
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Affiliation(s)
- F Lamberti
- Department of Industrial Engineering (DII), University of Padova , Via Gradenigo 6a, 35131 Padova, Italy
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8
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Tanaka M, Sawaguchi T, Kuwahara M, Niwa O. Surface modification of silicon oxide with trialkoxysilanes toward close-packed monolayer formation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:6361-6368. [PMID: 23668922 DOI: 10.1021/la4009834] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
In order to scrutinize potential of trialkoxysilanes to form close-packed monolayer, surface modification of silicon oxide was carried out with the trialkoxysilanes bearing a ferrocene moiety for analysis by electrochemical methods. As it was found that hydrogen-terminated silicon reacts with trialkoxysilane through natural oxidation in organic solvents, where the silicon oxide layer is thin enough to afford conductivity for electrochemical analysis, hydrogen-terminated silicon wafer was immersed in trialkoxysilane solution for surface modification without oxidation treatment. Cyclic voltammetry measurements to determine surface concentrations of the immobilized ferrocene-silane on silicon surface were carried out with various temperature, concentration, solvent, and molecular structure, while the blocking effect in the cyclic voltammogram was investigated to obtain insight into density leading to the close-packed layer. The results suggested that a monolayer modification tended to occur under milder conditions when the ferrocene-silane had a longer alkyl chain, and formation of a close-packed layer to show significant blocking effect was observed. However, the surface modification proceeded even when surface concentration of the immobilized ferrocene-silane was greater than that expected for the monolayer. On the basis of these tendencies, the surface of silicon oxide modified with trialkoxysilane is considered to be a partial multilayer rather than monolayer although a close-packed layer is formed. This result is supported by the comparison with carbon surface modified with ferrocene-diazonium, in which a significant blocking effect was observed when surface concentrations of the immobilized ferrocene moiety are lower than that for silicon oxide modified with ferrocene-silane.
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Affiliation(s)
- Mutsuo Tanaka
- Biomedical Research Institute, Advanced Industrial Science and Technology, Central 6, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan.
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9
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Surface Intiated Atom Transfer Radical Polymerizations from Indium Tin Oxide Electrodes: Electrochemistry of Polymer Brushes. ACTA ACUST UNITED AC 2012. [DOI: 10.1021/bk-2012-1101.ch013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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10
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Losego MD, Guske JT, Efremenko A, Maria JP, Franzen S. Characterizing the molecular order of phosphonic acid self-assembled monolayers on indium tin oxide surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:11883-11888. [PMID: 21863828 DOI: 10.1021/la201161q] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Self-assembled monolayers (SAMs) of alkanephosphonic acids with chain lengths between 8 and 18 carbon units were formed on thin films of indium tin oxide (ITO) sputter-deposited on silicon substrates with 400 nm thermally grown SiO(2). The silicon substrates, while not intended for use in near-IR or visible optics applications, do provide smooth surfaces that permit systematic engineering of grain size and surface roughness as a function of the sputter pressure. Argon sputter pressures from 4 to 20 mTorr show systematic changes in surface morphology ranging from smooth, micrometer-sized grain structures to <50 nm grains with 3× higher surface roughness. Near-edge X-ray absorption fine structure (NEXAFS) spectroscopy experiments are conducted for alkanephosphonic acids deposited on these wide range of ITO surfaces to evaluate the effects of these morphological features on monolayer ordering. Results indicate that long-chain SAMs are more highly ordered, and have a smaller tilt angle, than short-chain SAMs. Surprisingly, the 1-octadecyl phosphonic acids maintain their order as the lateral grain dimensions of the ITO surface shrink to ∼50 nm. It is only when the ITO surface roughness becomes greater than the SAM chain length (∼15 Å) that SAMs are observed to become relatively disordered.
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Affiliation(s)
- Mark D Losego
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695-8204, USA
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Chen X, Chockalingam M, Liu G, Luais E, Gui AL, Gooding JJ. A Molecule with Dual Functionality 4-Aminophenylmethylphosphonic Acid: A Comparison Between Layers Formed on Indium Tin Oxide by In Situ Generation of an Aryl Diazonium Salt or by Self-Assembly of the Phosphonic Acid. ELECTROANAL 2011. [DOI: 10.1002/elan.201100337] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Simão C, Mas-Torrent M, Crivillers N, Lloveras V, Artés JM, Gorostiza P, Veciana J, Rovira C. A robust molecular platform for non-volatile memory devices with optical and magnetic responses. Nat Chem 2011; 3:359-64. [DOI: 10.1038/nchem.1013] [Citation(s) in RCA: 177] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2010] [Accepted: 02/17/2011] [Indexed: 12/27/2022]
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Chockalingam M, Darwish N, Le Saux G, Gooding JJ. Importance of the indium tin oxide substrate on the quality of self-assembled monolayers formed from organophosphonic acids. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:2545-2552. [PMID: 21314169 DOI: 10.1021/la104464w] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The role of indium tin oxide (ITO) surface structure and chemistry on the formation of self-assembled monolayers (SAM) derived from organophosphonic acids has been investigated. The surface hydroxide content, crystal structure, and roughness of unmodified ITO surfaces were analyzed with X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), atomic force microscopy (AFM), and contact angle measurements. Organophosphonic acid monolayer modified ITO surfaces were then characterized using electrochemistry, contact angle measurements and impedance spectroscopy. To ascertain the extent of defects, Pb was underpotentially deposited (UPD) onto the monolayer modified ITO surfaces at defect sites and regions where the monolayer was weakly bound. The extent of defects, and the location of defects, in monolayers formed on different ITO surfaces were determined from the amount of charge passed during UPD of Pb at identical conditions, followed by XPS analysis of the Pb 4f peak and imaging with scanning tunnelling microscopy (STM). The results demonstrate that the crystal structure and hydroxide ion concentration of ITO surfaces significantly influence the quality of self-assembled monolayer formation as does the surface roughness. The most well-packed stable monolayers formed only on smooth amorphous ITO substrates with homogeneous grains and high hydroxide content. Lower quality SAMs with significant defects formed on polycrystalline surfaces and the higher the roughness the more the defects. STM defect mapping revealed that the location of defects in monolayers occurred at the boundaries between grain edges on the polycrystalline surfaces. This shows that the substrate characteristics have a strong influence on the quality of monolayers formed on ITO surfaces.
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Rider DA, Tucker RT, Worfolk BJ, Krause KM, Lalany A, Brett MJ, Buriak JM, Harris KD. Indium tin oxide nanopillar electrodes in polymer/fullerene solar cells. NANOTECHNOLOGY 2011; 22:085706. [PMID: 21242635 DOI: 10.1088/0957-4484/22/8/085706] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Using high surface area nanostructured electrodes in organic photovoltaic (OPV) devices is a route to enhanced power conversion efficiency. In this paper, indium tin oxide (ITO) and hybrid ITO/SiO(2) nanopillars are employed as three-dimensional high surface area transparent electrodes in OPVs. The nanopillar arrays are fabricated via glancing angle deposition (GLAD) and electrochemically modified with nanofibrous PEDOT:PSS (poly(3,4-ethylenedioxythiophene):poly(p-styrenesulfonate)). The structures are found to have increased surface area as characterized by porosimetry. When applied as anodes in polymer/fullerene OPVs (architecture: commercial ITO/GLAD ITO/PEDOT:PSS/P3HT:PCBM/Al, where P3HT is 2,5-diyl-poly(3-hexylthiophene) and PCBM is [6,6]-phenyl-C(61)-butyric acid methyl ester), the air-processed solar cells incorporating high surface area, PEDOT:PSS-modified ITO nanoelectrode arrays operate with improved performance relative to devices processed identically on unstructured, commercial ITO substrates. The resulting power conversion efficiency is 2.2% which is a third greater than for devices prepared on commercial ITO. To further refine the structure, insulating SiO(2) caps are added above the GLAD ITO nanopillars to produce a hybrid ITO/SiO(2) nanoelectrode. OPV devices based on this system show reduced electrical shorting and series resistance, and as a consequence, a further improved power conversion efficiency of 2.5% is recorded.
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Affiliation(s)
- David A Rider
- National Institute for Nanotechnology, National Research Council, Edmonton, AB, Canada
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15
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Eckermann AL, Feld DJ, Shaw JA, Meade TJ. Electrochemistry of redox-active self-assembled monolayers. Coord Chem Rev 2010; 254:1769-1802. [PMID: 20563297 PMCID: PMC2885823 DOI: 10.1016/j.ccr.2009.12.023] [Citation(s) in RCA: 357] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Redox-active self-assembled monolayers (SAMs) provide an excellent platform for investigating electron transfer kinetics. Using a well-defined bridge, a redox center can be positioned at a fixed distance from the electrode and electron transfer kinetics probed using a variety of electrochemical techniques. Cyclic voltammetry, AC voltammetry, electrochemical impedance spectroscopy, and chronoamperometry are most commonly used to determine the rate of electron transfer of redox-activated SAMs. A variety of redox species have been attached to SAMs, and include transition metal complexes (e.g., ferrocene, ruthenium pentaammine, osmium bisbipyridine, metal clusters) and organic molecules (e.g., galvinol, C(60)). SAMs offer an ideal environment to study the outer-sphere interactions of redox species. The composition and integrity of the monolayer and the electrode material influence the electron transfer kinetics and can be investigated using electrochemical methods. Theoretical models have been developed for investigating SAM structure. This review discusses methods and monolayer compositions for electrochemical measurements of redox-active SAMs.
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Krause KM, Taschuk MT, Harris KD, Rider DA, Wakefield NG, Sit JC, Buriak JM, Thommes M, Brett MJ. Surface area characterization of obliquely deposited metal oxide nanostructured thin films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:4368-4376. [PMID: 20000633 DOI: 10.1021/la903444e] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The glancing angle deposition (GLAD) technique is used to fabricate nanostructured thin films with high surface area. Quantifying this property is important for optimizing GLAD-based device performance. Our group has used high-sensitivity krypton gas adsorption and the complementary technique of cyclic voltammetry to measure surface area as a function of deposition angle, thickness, and morphological characteristics for several metal oxide thin films. In this work, we studied amorphous titanium dioxide (TiO(2)), amorphous silicon dioxide (SiO(2)), and polycrystalline indium tin oxide (ITO) nanostructures with vertical and helical post morphologies over a range of oblique deposition angles from 0 to 86 degrees. Krypton gas sorption isotherms, evaluated using the Brunauer-Emmettt-Teller (BET) method, revealed maximum surface area enhancements of 880 +/- 110, 980 +/- 125, and 210 +/- 30 times the footprint area (equivalently 300 +/- 40, 570 +/- 70, and 50 +/- 6 m(2) g(-1)) for vertical posts TiO(2), SiO(2), and ITO. We also applied the cyclic voltammetry technique to these ITO films and observed the same overall trends as seen with the BET method. In addition, we applied the BET method to the measurement of helical films and found that the surface area trend was shifted with respect to that of vertical post films. This revealed the important influence of the substrate rotation rate and film morphology on surface properties. Finally, we showed that the surface area scales linearly with film thickness, with slopes of 730 +/- 35 to 235 +/- 10 m(2) m(-2) microm(-1) found for titania vertical post films deposited at angles from 70 to 85 degrees. This characterization effort will allow for the optimization of solar, photonic, and sensing devices fabricated from thin metal oxide films using GLAD.
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Affiliation(s)
- Kathleen M Krause
- Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta, Canada T6G 2V4.
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17
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Kim BY, Ratcliff EL, Armstrong NR, Kowalewski T, Pyun J. Ferrocene functional polymer brushes on indium tin oxide via surface-initiated atom transfer radical polymerization. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:2083-2092. [PMID: 19968255 DOI: 10.1021/la902590u] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The synthesis and electrochemical characterization of ferrocene functional polymethacrylate brushes on indium tin oxide (ITO) electrodes using surface-initiated atom transfer radical polymerization (SI-ATRP) is reported. SI-ATRP of ferrocene-containing methacrylate (FcMA) monomers from a phosphonic acid initiator-modified ITO substrate yielded well-defined homo- and block (co)polymer brushes of varying molar mass (4,000 to 37,000 g/mol). Correlation of both electrochemical properties and brush thicknesses confirmed controlled SI-ATRP from modified ITO surfaces. The preparation of block copolymer brushes with varying sequences of FcMA segments was conducted to interrogate the effects of spacing from the ITO electrode surface on the electrochemical properties of a tethered electroactive film.
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Affiliation(s)
- Bo Yun Kim
- Department of Chemistry, University of Arizona, 1306 E. University Boulevard, Tucson, Arizona 85721, USA
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18
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Motiei L, Lahav M, Gulino A, Iron MA, van der Boom ME. Electrochemical Characteristics of a Self-Propagating Molecular-Based Assembly. J Phys Chem B 2010; 114:14283-6. [DOI: 10.1021/jp910898f] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Leila Motiei
- Departments of Organic Chemistry and Chemical Research Support, The Weizmann Institute of Science, 76100 Rehovot, Israel, and Department of Chemistry, University of Catania, 95125 Catania, Italy
| | - Michal Lahav
- Departments of Organic Chemistry and Chemical Research Support, The Weizmann Institute of Science, 76100 Rehovot, Israel, and Department of Chemistry, University of Catania, 95125 Catania, Italy
| | - Antonino Gulino
- Departments of Organic Chemistry and Chemical Research Support, The Weizmann Institute of Science, 76100 Rehovot, Israel, and Department of Chemistry, University of Catania, 95125 Catania, Italy
| | - Mark A. Iron
- Departments of Organic Chemistry and Chemical Research Support, The Weizmann Institute of Science, 76100 Rehovot, Israel, and Department of Chemistry, University of Catania, 95125 Catania, Italy
| | - Milko E. van der Boom
- Departments of Organic Chemistry and Chemical Research Support, The Weizmann Institute of Science, 76100 Rehovot, Israel, and Department of Chemistry, University of Catania, 95125 Catania, Italy
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19
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Miozzo L, Yassar A, Horowitz G. Surface engineering for high performance organic electronic devices: the chemical approach. ACTA ACUST UNITED AC 2010. [DOI: 10.1039/b922385a] [Citation(s) in RCA: 124] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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20
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Armstrong NR, Veneman PA, Ratcliff E, Placencia D, Brumbach M. Oxide contacts in organic photovoltaics: characterization and control of near-surface composition in indium-tin oxide (ITO) electrodes. Acc Chem Res 2009; 42:1748-57. [PMID: 19728725 DOI: 10.1021/ar900096f] [Citation(s) in RCA: 156] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The recent improvements in the power conversion efficiencies of organic photovoltaic devices (OPVs) promise to make these technologies increasingly attractive alternatives to more established photovoltaic technologies. OPVs typically consist of photoactive layers 20-100 nm thick sandwiched between both transparent oxide and metallic electrical contacts. Ideal OPVs rely on ohmic top and bottom contacts to harvest photogenerated charges without compromising the power conversion efficiency of the OPV. Unfortunately, the electrical contact materials (metals and metal oxides) and the active organic layers in OPVs are often incompatible and may be poorly optimized for harvesting photogenerated charges. Therefore, further optimization of the chemical and physical stabilities of these metal oxide materials with organic materials will be an essential component of the development of OPV technologies. The energetic and kinetic barriers to charge injection/collection must be minimized to maximize OPV power conversion efficiencies. In this Account, we review recent studies of one of the most common transparent conducting oxides (TCOs), indium-tin oxide (ITO), which is the transparent bottom contact in many OPV technologies. These studies of the surface chemistry and surface modification of ITO are also applicable to other TCO materials. Clean, freshly deposited ITO is intrinsically reactive toward H(2)O, CO, CO(2), etc. and is often chemically and electrically heterogeneous in the near-surface region. Conductive-tip atomic force microscopy (C-AFM) studies reveal significant spatial variability in electrical properties. We describe the use of acid activation, small-molecule chemisorption, and electrodeposition of conducting polymer films to tune the surface free energy, the effective work function, and electrochemical reactivity of ITO surfaces. Certain electrodeposited poly(thiophenes) show their own photovoltaic activity or can be used as electronically tunable substrates for other photoactive layers. For certain photoactive donor layers (phthalocyanines), we have used the polarity of the oxide surface to accelerate dewetting and "nanotexturing" of the donor layer to enhance OPV performance. These complex surface chemistries will make oxide/organic interfaces one of the key focal points for research in new OPV technologies.
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Affiliation(s)
- Neal R. Armstrong
- Department of Chemistry, University of Arizona, Tucson, Arizona 85721
| | - P. Alex Veneman
- Department of Chemistry, University of Arizona, Tucson, Arizona 85721
| | - Erin Ratcliff
- Department of Chemistry, University of Arizona, Tucson, Arizona 85721
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21
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Kessler D, Lechmann MC, Noh S, Berger R, Lee C, Gutmann JS, Theato P. Surface Coatings Based on Polysilsesquioxanes: Solution-Processible Smooth Hole-Injection Layers for Optoelectronic Applications. Macromol Rapid Commun 2009; 30:1238-42. [DOI: 10.1002/marc.200900196] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2009] [Accepted: 04/27/2009] [Indexed: 11/10/2022]
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22
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DiBenedetto SA, Facchetti A, Ratner MA, Marks TJ. Charge Conduction and Breakdown Mechanisms in Self-Assembled Nanodielectrics. J Am Chem Soc 2009; 131:7158-68. [DOI: 10.1021/ja9013166] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Sara A. DiBenedetto
- Department of Chemistry and the Materials Research Center, Northwestern University, Evanston, Illinois 60208-3113
| | - Antonio Facchetti
- Department of Chemistry and the Materials Research Center, Northwestern University, Evanston, Illinois 60208-3113
| | - Mark A. Ratner
- Department of Chemistry and the Materials Research Center, Northwestern University, Evanston, Illinois 60208-3113
| | - Tobin J. Marks
- Department of Chemistry and the Materials Research Center, Northwestern University, Evanston, Illinois 60208-3113
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